1. Field of Invention
The present invention relates to antenna and more particularly to a fishbone-shaped patch antenna employed in radio communication base station for transmitting signals to mobile terminal and receiving signals from mobile terminal with increased half-power beamwidth in the horizontal plane.
2. Related Art
Mobile phones have become popular in recent years. More people use it as a necessary communication means in daily life. In use, mobile phone has a similar function as wired telephone. That is, mobile phone can effect a two-way communication. Further, each mobile phone has a unique number. Each mobile phone user can make a call to a called party by transmitting encoded signals via base station.
It is understood that most base stations effect a cellular communication principle. That is a high power transmitter for covering all areas is replaced by employing a plurality of low power transmitters in many sectors called cells. As such, many cells are employed to ensure a sufficient communication quality and desired transmitting and receiving ranges. In view of this, transmission power of base station and horizontal and vertical angle ranges of antenna are important factors. It is desired that a cost-effective design may be effected by employing a small number of antennas to obtain a wider transmission and receiving ranges.
A prior art rectangular patch antenna 10 is shown in FIG. 1 comprising a slot coupled microstrip patch antenna 20 made of low loss dielectric plate having a microstrip 21 in rear and a gap or slot 22 in front being connected to signal source (not shown) through a conductor 40; a reflector 30 made of metal plate being non-electrically connected to the rear of slot coupled microstrip patch antenna 20 so as to cause rearward radiated electromagnetic waves to reflect forward; and a resonant member 11 in front of and being non-electrically connected to slot coupled microstrip patch antenna 20 so as to increase directivity, operation band width, an d power of electromagnetic waves.
Signals transmitted by above antenna have a half-power beamwidth with average value of 60.degree.-70.degree. in the center or a maximum value of 80.degree. in the horizontal plane. As such, it is impossible to obtain a wider transmission and receiving ranges by such conventional rectangrular antenna.